Process for preparing sterols from tall oil pitch

ABSTRACT

Process for preparing sterols from plant sources, especially tall oil pitch, by extraction in a water-alcohol-hydrocarbon mixture followed by saponification and subsequent recrystallization and leaching.

United States Patent Julian 1 Sept. 12, 197 2 PROCESS FOR PREPARINGSTEROLS [56] References Cited FROM TALL OIL PITCH UNITED STATES PATENTS[72] Inventor: Donald V. Julian, Colerain Township Hamilton, i 2,865,93412/1958 Fisher ..260/397.25

[73] Assignee: f m Famble Company Primary Examiner-Elbert L. RobertsCmcmnau ohm Attorney-Jack D. Schaeffer and Richard C. Witte [22] Filed:Dec. 7, 1970 [57] ABSTRACT [21] Appl. No.: 95,735

Process for preparing sterols from plant sources, especially tall oilpitch, by extraction in a water-alcohol- [52] US. Cl ..260/397.25hydrocarbonmixture followed by saponification and [51] Int. Cl ..C07c167/38 Subsequent recrystallization and leaching [58] Field of Search..260/397.25

6 Claims, 2 Drawing Figures (I) Alcohol- Hydrocarbon Solvent (2) WaterSterol Source (Pitch) (A) Concentration of Sterol Water-Alcohol AcidEsters by Dissolution LuyeHAcids Recovery and Phase Separation (AcidRemoval) Hydrocarbon Layer (Sterol Esters) Hydrocarbon 'Recovery (B)Saponificotion of Sterol Esters (C) Recovery of Crude SupomflcmlonSterols By-products Crude Sterols (D) (l)| b purification by nso u les(Soups) and Dissolu'ion and Oxidized Material Leaching (2) HighMolecular Weight Alcohols Purified Sterols SHEET 1 [)F 2 Fig. l

Sterol Source (Pitch) (A) (l) Alcohol- Concentration of SterolWater-Alcohol Acid ggsgr Esters by Dissolution L0yer+Acids Recovery (2)water and Phase Separation (Acid Removal) Hydrocarbon Layer (SterolEsters) Hydrocarbon Recovery (B) Saponification of Sterol Esters (C)Recovery of Crude sopon'f'cm'on Sterols Byproducts Crude Sterols (D) (HmI bl (s d Purification by sou e5 PS an Dissolution and OxidizedMflieriol Leaching (2 High Molecular Purified Sterols Weight AlcoholsINVENTOR.

Donald V. Julian ATTORNE Y PATENTED SEP 1 2 I972 SHEET 2 BF 2 Fig. 2

l I20 INVENTOR.

Donald V. Julian Temperature F 2 2925 B E52 m ATTORNEY PROCESS FORPREPARING STEROLS FROM TALL OIL PITCH BACKGROUND OF THE INVENTIONstances of biological importance. While animal fats and [0 oils may besuitably treated and sterols recovered therefrom, certain plant sourcesare more attractive natural sources of these complex materials, both byvirtue of cost and quantity of sterol present. Too, certain sterols arefound only in plants and are not obtainable from animal sources.

Sterols have been isolated from such diverse plant sources as corn oil,wheat germ oil, sarsaparilla root, soybean pitch and corn oil pitch.These latter substances appear to be enriched in sterol content byvirtue of the prior treatment of the raw materials from which they areobtained. For example, tall oil pitch is obtained during the process ofpreparing paper from wood, particularly pine wood, and contains up topercent sterol esters. Tall oil pitch is an extremely complex materialcomprising rosins, fatty acids, oxidation products and esterifiedmaterials, an appreciable fraction of which are sterol esters. As can beseen from the foregoing, these plant sources of sterols are inexpensivein that they are the foots or tailings left from various manufacturingprocesses. It is also apparent that these pitches are extremely complexmixtures and that to recover high molecular weight sterols therefrom ingood yields and high purities requires superior purification techniques.

Any of the plant oil tailings or pitches, especially those hereindescribed, are suitable sources for sterols U.S. Pat. No. 2,715,638,Aug. l6, 1955, to Albrecht and Herrlinger, discloses a process forrecovering sterols from tall oil pitch whereby the fatty acid impuritiesare removed by a neutralization process. Following this, the sterolesters are saponified; the free sterols are then recovered and washedwith isopropanol and dried.

U.S. Pat. No. 2,573,891, Nov. 6, 1951, to Christenson, describes aprocess for recovering sterols from pitch fractions wherein the removalof unesterified fatty acids is accomplished by extraction with atwophase solvent system comprising a hydrocarbon fraction and a polarsolvent containing water. Because of the two-phase solvent system, it isnecessary to employ good mixing or, preferably, counter-currentextraction procedures when this method of purification is employed.

It is important to the ultimate purity of the sterols recovered fromplant sources (e.g., pitches) that all of the free fatty acids and fattyalcohols be removed therefrom. To achieve maximum sterol yields, it isimportant that the sterol esters present in the sterol when treated inthe manner of this invention since all of these sterol sources containmuch the same impurities and by-products which must be removed duringthe sterol recovery process. Chief among these impurities are varioussaturated and unsaturated high molecular weight acids, such as oleicacid and stearic acid. These acids, themselves, have industrialimportance and, as is hereinafter disclosed, good recovery of theseacids can be had by the process of this invention and the plant oilpitches thereby made to serve not only as sterol sources, but also assources for commercially important fatty acids.

High molecular weight alcohols are another type of impurity found inmost plant sterol sources. Since the sterols, themselves, are highmolecular weight alcohols, their separation from the long-chain alcoholimpurities is particularly difficult. The process of this invention isespecially suited for removing these undesirable alcoholic materialsfrom the sterols.

Various methods for recovering sterols from plant sources have beendisclosed in the prior art. U.S. Pat. 2,835,682, May 20, 1958, toSteiner and'Fritz, discloses a process comprising the steps offractionating the sterol-containing composition in a liquid, normallygaseous hydrocarbon to obtain a sterol-enriched fraction, saponifyingthe sterol-enriched fraction to hydrolyze the sterol esters presenttherein and, finally, recovering the sterol. The process uses liquifiedpropane gas and is done under pressure at high temperatu'res.

source be completely saponified and broken down into their sterol andacid fragments. Finally, it is important that other impurities presentin the sterol source, especially oxidized materials arising from thevarious manufacturing processes from which these materials are derived,be removed from the sterols. Removal of these various contaminants isparticularly important when the sterols are to be ultimately used inmedical applications. Perhaps the most difficult impurities to removefrom the sterol source are the high molecular weight alcohols and theoxidized materials. Furthermore, the presence of extraneous acids duringsaponification of the sterol esters results in excessive consumption ofcaustic and economic waste. The prior art processes for the preparationof sterols from plant sources suffer from various difficulties,including the need for the use of high temperatures and pressures,specialized countercurrent extraction equipment, excessive causticconsumption, incomplete removal of the high molecular weight alcoholiccontaminants and the like.

The process of the present invention differs from those of the prior artin that good separation of the free fatty acids from the sterol sourceis accomplished without recourse to high pressure apparatus and withoutexcessive caustic use. Furthermore, since the organic solvent-sterolsolution employed herein is initially homogeneous, it is not necessaryto employ countercurrent extraction techniques when practicing thisprocess. Therefore, although this process can be run as a continuousoperation, it is especially suitable for batch operations. Also, thisprocess accomplishes the removal of high molecular weight alcohols fromthe sterols and produces very high purity sterols in high yields.

Accordingly, it is a primary object of the present invention to providean improved process for the preparation of high purity sterols in highyields from plant sources. It is a further object of this invention toprovide a method for removing acids and alcohols from sterols and sterolsources without recourse to the use of high temperatures, pressures orcomplicated extraction procedures. These and other objects are obtainedby the present invention as will become apparent from the followingdisclosure.

SUMMARY OF THE INVENTION The present invention relates to a process forpreparing sterols from plant sources, especially tall oil pitch,comprising the steps of: (A) acid removal; (B) saponification of sterolesters; (C) sterol recovery; and (D) purification by dissolution andleaching operations, all as hereinafter detailed.

REFERENCE TO DRAWINGS FIG. 1 is a flow chart depicting the individualoperations in the overall process of this invention.

FIG. 2 represents the approximate solubility-tem perature relationshipsof sterols and high molecular weight alcohols in various solvents andrelates to the final leaching step of the present process. Curve Ademonstrates sterol solubility in methanol; solubility in nitromethaneis somewhat lower. Curve B is the solubility curve for the impurities inthese solvents, including the high molecular weight alcohols. Curves Cand D demonstrate the approximate solubilities of typical sterols inethanol and iso-propanol, respectively. It is noted that only inmethanol and nitromethane is the solubility of the sterols less thanthat of the impurities such that the impurities can be leached from thesterols. It is further noted that at temperatures above about 70 F, thissolubility difference is greatly enhanced, thereby effecting animprovement in the leaching process above this critical temperature.

DETAILED DESCRIPTION OF THE INVENTION As outlined in FIG. 1, the processof the present invention comprises the steps of: (A) dissolving aplantderived sterol source (pitch) in a solvent mixture consisting ofalcohol and hydrocarbon; adding the proper amount of water; allowing thehydrocarbon phase (which contains the sterol esters) to separate fromthe water-alcohol phase (which contains the acids); (B) saponifying thesterol esters obtained from the hydrocarbon phase of step (A) with baseunder the conditions hereinafter detailed; (C) recovering the sterols;and (D) dissolving the sterols in a solvent, recovering the sterols andleaching the sterols with methanol or nitromethane at a temperaturewithin a critical range.

STEP A Separation of Sterol Esters and Acids One critical aspect of thepresent process is the alcohol-hydrocarbon solvent employed in step (A)for removingthe acids from the plant sterol source. Proper selection ofthe organic components of this solvent mixture and the relative ratiosthereof results in a homogeneous solution when the sterol source isdissolved therein. When water is added to this homogeneous solution itseparates into two layers, (1) the wateralcohol layer in which the fattyacids are dissolved and (2) the hydrocarbon layer wherein the sterolesters are dissolved. Thus, by using properly formulated mixed organicsolvents this step in the preparation of pure sterols from plantpitches, to wit, the removal of the fatty acids, is readily achieved.Organic solvent mixtures which are liquid at room temperatures andatmospheric pressures can be selected so that the need for specialpressure vessels and gas liquifying apparatus is obviated.

The mixed solvents used in step (A) are mixtures of alcohols andhydrocarbons as described below and are initially immiscible. However,when the sterol source is dissolved in these solvents they becomemiscible and a homogeneous system is formed. This homogeneous system isseparated into two phases (water-alcohol and hydrocarbon) when water isadded in the proportions hereinafter noted. The use of such homogeneous,water-separable solutions allows the separation and removal of fattyacids from the sterol source without recourse to the countercurrentextraction procedures needed when two-phase solvents are employed inthis step. Hence, step (A) of the instant process can be convenientlydone in a simple batch operation, if so desired; alternatively, standardcontinuous extraction processes can be employed with these mixedsolvents.

The hydrocarbons suitable for use in step (A) of this process includeliquid branched-chain, straight-chain and cyclic hydrocarbons containingfrom about five to about 20 carbon atoms and mixtures thereof, forexample, kerosenes, petroleum ethers, light mineral oils and the like.Lower molecular weight hydrocarbons, such as methane, ethane, propaneand butane can be employed in this step but must be used in theliquified state, i.e., under pressure, and are therefore not preferred.Exemplary hydrocarbons suitable for use in the mixed solvent of step (A)are pentane, hexane, heptane, octane, nonane, decane, undecane,dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane,octadecane, nonadecane, eicosane, 2- methylpentane, Z-methylhexane,3-ethylheptane, 3- ethyloctane, 2,3-dimethylnonane, 3,4-diethyl-decane,isooctane, cyclopentane, cyclohexane, cyclodecane and mixtures of thesehydrocarbons. Benzene, toluene and the xylenes are also suitablyemployed as the hydrocarbon component of the hydrocarbon-alcohol solventused herein in step (A). An especially preferred hydrocarbon componentof the mixed organic solvent used in step (A) to remove the acids fromthe vegetable sterol sources is hexane. Kerosene and petroleum ethers,both high and low boiling, are also preferred.

Alcohols suitable for use herein in step (A) include those alcoholscontaining from one to about six carbon atoms, more preferably from oneto about three carbon atoms. Non-limiting examples of alcohols suitablefor such use include methanol, ethanol, propanol, isopropanol, butanol,t-butanol, pentanol, hexanol and isohexanol. Especially preferredalcohols for use in the fatty acid removal step (A) of the presentprocess are methyl alcohol and ethyl alcohol.

Preferred mixed alcohol-hydrocarbon solvents used herein in step (A)include hexane-methanol, kerosenemethanol, petroleum ether-ethanol,petroleum ethermethanol and hexane-ethanol. The ratio ofalcoholzhydrocarbon in the mixed solvent can range from about 5:1 to 1:5and is preferably about 1:1 on a weight basis.

As is noted above, these solvent mixtures are initially heterogeneousand become homogeneous when the sterol source is dissolved therein.Water, in the proper partitioned into the hydrocarbon phase along withthe sterol and the purification efficiency is decreased. If too littlewater is used, incomplete phase separation results and some sterolesters remain with the alcoholwater phase and are lost. The amount ofwater used to cause a separation of the alcohol-hydrocarbonvsterolsource solution is fairly critical and is within the range from about0.5 percent by weight of alcohol to about percent by weight of alcohol,more preferably from about 1.5 to about 6 percent, by weight of alcoholpresent in the mixed hydrocarbon-alcohol solvent.

The ratio of solvent to plant pitch in step (A) is not critical and canbe in the range of about 50:1 to about 2:1, more preferably from about:1 to about 5:1. Higher solvent-to-pitch ratios could be employed butthe percentage of acid extracted does not show a corresponding increase.In a commercial process it is best to avoid large excesses of solvent soas to minimize handling and recovery problems. Lower solvent:pitchratios result in inconveniently slow dissolution of pitch.

The extraction procedure used to remove free acids from the sterolesters involves dissolving the plant pitch in the organic solventmixture, whereupon, after addition of water, the solvent separates intoan upper, hydrocarbon layer which contains the sterol esters and alower, alcohol-water phase containing the acids. The layers are thenseparated mechanically. The hydrocarbon is evaporated to yield nearlyacid-free sterol esters and the hydrocarbon can be recovered for reuse.The alcohol-water layer containing the fatty acid can be evaporated andthe acids and alcohols thereby separated and recovered.

Step (A) of this invention can be performed at any convenienttemperature, most generally from about 32F to about 2l2F, morepreferably from about 32F to about 90F. Obviously, at the highertemperatures many of the hydrocarbons would be lost by evaporation andwhen such high temperatures are employed the reaction should be done ina sealed vessel. Operating pressures are not critical in step (A), or inany of the subsequent steps of the present process.

STEP B Saponification of Sterol Esters Step (B) of the present processinvolves the saponification of the sterol esters recovered from thehydrocarbon layer from step (A) with base and comprises charging thepartially purified sterol esters from step (A), base and asaponification solvent into a reaction vessel and heating this mixtureat an appropriate temperature for an appropriate ,period of time, all ashereinafter detailed. The requirements for the saponification solventused in step (B) are: (1) it must solubilize the reactants; (2) it mustbe inert to the reactants; and (3) it must be easily recoverable.Furthermore, if the sterols are to be ultimately used in medical or foodproducts, the saponification solvents employed should be suitable forfood processing, i.e., non-toxic and innocuously flavored. The loweralcohols, e. g., methanol, ethanol, isopropanol, etc., fulfill thesesolvent requirements and are suitable for use as the saponificationsol-' vent in step (B) and are convenient in that the free sterolsresulting from the saponification are relatively insoluble therein andreadily separable. Methanol is especially preferred for this use.

The base used in the saponification of the sterol esters can be any ofthe alkali metal bases, i.e., lithium hydroxide, sodium hydroxide,potassium hydroxide, rubidium hydroxide and cesium hydroxide, withsodium hydroxide and potassium hydroxide being preferred from a coststandpoint. Lime (calcium oxide), although a less expensive source ofcaustic, is not suitable since calcium soaps are formed and these areinsoluble in the systemand contaminate the product.

The amount of base used in the saponification appears to effect the timeneeded for the completion of the reaction. A 0.1-fold to 4-fold molarexcess of base can be employed in the saponification with about a 0.7-fold to about a l-fold molar excess being preferred. To demonstrate thetime differential when various amounts of base are employed, 30 minutesare required to completely saponify sterol esters using a 3.5-fold molarexcess of base, compared with 1.5 hours reaction time using a l-foldmolar excess of base, when the reaction is run at 300F.

While the sterol esters can be saponified with excess base over atemperature range of from about F to about 500F, temperatures in thelower portion of this range are not satisfactory to effect completehydrolysis of said esters and economic loss of unsaponified sterolesters is incurred if the lower temperatures within this range areemployed in the saponification. Therefore, it is more preferable toemploy temperatures above 300F to effect the saponification. It israrely necessary to exceed 500F to insure completion of thissaponification; hence a saponification temperature in the range from300F to 500F is preferred herein and is critical if optimum productyields are to be achieved. Of course, at these higher temperatures aclosed reaction vessel must be'used to contain the alcohol solvent.Pressures in the closed vessels will range from about p.s.i.a. to about1,500 p.s.i.a. due to the containment of the solvent vapors at thesetemperatures. However, these pressures are not critical and do notaffect the course of the reaction. The time of the reaction is notcritical thereto and can range from a few minutes to a few hours. Asnoted hereinabove, almost 100 percent saponification of the sterols canbe achieved in 30 minutes at 300F using a 3.5-fold molar excess of baseand it is unnecessary to exceed this time greatly. Good, but notquantitative, yields of free sterol can be achieved under theseconditions in from 2 to l0 minutes if speed of the reaction, rather thantotal sterol recovery, is the primary consideration.

STEP C Recovery of Crude Sterols Step (C) of the present processinvolves the separation of the free sterols from the alcoholicsaponification reaction mixture. Sterols are, in general, relativelyinsoluble in alcohols and can be recovered by standard filtration andcentrifugation techniques. After separation, the sterols can,optionally, be washed with water. Improved recovery of the sterols canbe had if a little water is added to the alcoholic saponificationmixture upon completion of the saponification reaction since the sterolsare less soluble in aqueous-alcohol than in pure alcohol. However, itmust be noted that adding a large quantity of water before centrifugingor filtering the sterols increases the sterol recovery but also causesmore impurities such as long-chain fatty acids to precipitate andcontaminate the sterols. It is to be understood that quite good sterolrecoveries can be achieved from any of the alcohols disclosed herein foruse as the saponification solvent, but that when from about percent toabout percent water (by weight of alcohol) is added to thesaponification mixture, better yields of sterol are secured since thesterols are less soluble in aqueous-alcohol than in pure alcohol.

STEP D Purification Step (D) of the present process is designed toremove metal soaps, oxidation products and high molecular weightalcohols from the sterols. This final purification step (D) comprisestwo stages and leads to sterols of very high purity. In the first stagethe wet, solid sterols from step (C) are preferably dried. This can beaccomplished, for example, by spray or roll drying, the advantage ofspray drying being that the dry solids will have a high surface area fordissolution in the next process step. (Alternatively, the sterols can beused wet, but this leads to operational difficulties and solventcontamination.) The solids are then contacted with a solvent, the onlyrequirement of such solvent being that the sterols are soluble thereinand that soaps, i.e., the salts of fatty acids, are insoluble therein.Following dissolution of the sterols and high molecular weight alcoholsin said solvent, the insolubles (soaps, etc.) are removed physically,i.e., by centrifugation, filtration, skimming, etc. The solvent isthenevaporated to yield fairly pure sterols contaminated with some highmolecular weight alcohols.

When performing this first stage of the purification step (D), it is notnecessary that any particular dissolution temperature be used. However,it will be-recognized that the sterols dissolve more rapidly, and theprocess is thereby speeded, when the solvent is heated. It is thereforepreferred that the dissolution of the sterol in the solvent be done withthe solvent refluxing at atmospheric pressure. As is hereinbefore noted,the solvent used in the first stage of step (D) is selected so that thesterols are soluble therein and any soaps and oxidized materials areinsoluble. it is understood that there are a wide variety of polar,aprotic organic solvents having these necessary solubilizingcharacteristics, among which are included the halogenated hydrocarbons,carbonyl compounds, especially ketones, and a variety of other organicmaterials such as the N,N-dialkyl-amides, for example dimethylformamide.The most preferred solvents for dissolving the sterols, therebyseparating them from the insoluble soaps, are acetone, methyl ethylketone and ethylene dichloride.

The second stage involved in the purification step (D) is the removal ofany high molecular weight alcohols and other minor contaminantscopresent with the sterols by a leaching process whereby thesecontaminants are selectively dissolved, and the pure, insoluble sterolsare retained. As is hereinbefore noted, this leaching stage of step (D)is complicated by the fact that the high molecular weight alcohols arechemically similar to the sterols and it is, therefore, difficult toseparate these materials. To prepare sterols of the highest purity byremoval of the high molecular weight alcoholic contaminants it isnecessary to employ a critical solvent. To this end, advantage is takenof the fact that said alcohols and oxidation product contaminants aremainly polar materials which are soluble in certain polar materials suchas alcohols or nitromethane. However as is noted by reference to FIG. 2,the sterols are more soluble than the alcoholic impurities in the higheralcohols and, thus, the only alcohol suitable for purifying the sterolsby this leaching process is methanol. As is further noted in FIG. 2, thesolubility differences between the contaminating high molecular weightalcohols and the sterols in methanol and nitromethane is accentuatedover certain temperature ranges having no apparent upper limit. Hence,methanol or nitromethane can be used at temperatures above about F toremove the high molecular weight alcohols and other impurities; the puresterols, which are relatively insoluble at these temperatures and inthese solvents, are retained.

The leaching stage of step (D) of the present process is carried out bycontacting the solid sterols with methanol or nitromethane at atemperature above about 70F, conveniently 70F to 300F, more preferablyfrom 70F to about F; pressure vessels can be employed and the leachingpressure is not critical. The solvents are then removed, hot, along withthe dissolved contaminating high molecular weight alcohols. Thisleaching can be repeated, as necessary. Alternatively, automaticextraction equipment can be used in this stage at the temperature rangesdetailed to provide continuous removal of the contaminating highmolecular weight alcohols from the sterols. Following this, the puresolid sterols allowed to dry, and the process is complete.

As is hereinbefore noted, any of the common plant sources of sterolesters can be employed in this process, with the various pitches andtailings being preferred, since all of these sterol sources contain muchthe same impurities. Non-limiting examples of sterol ester-containingplant sources suitable for use herein are: tall oil pitch, crude talloil, sugar cane oil, hot well skimmings, cottonseed pitch, soybeanpitch, corn oil pitch, wheat germ oil and rye germ oil; preferred istall oil pitch.

The following examples serve to illustrate the present process but arenot intended to be limiting thereof.

EXAMPLE I Step A Tall oil pitch (30.3 lbs.) was dissolved in hexane 121lbs.) with heating and mixing and then mixed with methanol (1 19 lbs.)with a nitrogen sparge; the ratio of solvent to pitch was 8:1 water (2.3lbs.) was then added. The lower layer (acid phase) which formed onstanding was drawn-off after the mixture had stood overnight at 70F.

Step B The hexane was stripped from the upper ester layer under vacuumand the solids were charged into an autoclave with sodium hydroxide (3.4lbs.) and methanol (22.8 lbs.). The reaction mixture was heated at 300Ffor 1.5 hours with continuous stirring.

9 StepC 'The' saponified mixture '-was'-dilute'd with water-( 86 solids'were dried i'n avacuumovemat 130%.

Step-D 'l'he=dried, centrituged solids' were' refluxed in methyl"wasdriediin-avacuum oven. v I I fThe dried residu'e from the M814solution was refluxed- -in methanol for "1 "hour. 'The'slurrywas thehfilmethanol. The leached "solids-K filtercakywere' dried in solids were92 Ipercerit frce 'sterol withEan 8 0 iper'cetit overall recover-y ofste'rol. iFhe -"s'terolsfobt ained in this fashion Iproved 't'o beipredor'ninately ifi-sitos'terdl and campeste'rol.

ln the above pro'ce'ssthe tall' oil {pitch is replaced *by :a e uivalentamount Oic'rudetallbilfsugarfcane oil, hot we'll "skimmings, cottonseeds-pitch, soybean i it'h, corn oil pitch, wheat i-ge'rr'n "oil, rye*fge'r'm oil, and j sar- :saparilla "root and equivalent resu'lts are="dbtained in that 'free ste'rols,*especially :B-sitostero'l arerecovered in agoo'd yields and high.pu'rities a'ndaref'frc'dfromcontaminatin g carboxylic acids andhigh rriolectilar' weight alcohols.

EXAM-PUE-Il Step-A Tall an pitch (5 l bsi) is "dissolved in high boilingpetroleum ether lbs.') -wit'h heati ng and methanol water- (0.3 lbs.)and some-additionalmethanol ('5 lbs!) The solids are removed byfiltra'tion a'nd dried under forced air at 120F.

"Step D The dried so'lids are refluxed i 'ethyl'ene dicli'lo'rideand'filtered hot througha frittediglass disk. The'insolu- "bles"(soapsfi are disc'a'rded and the liqu'id phase is evaporatedytheresidue-isdried at roomtemperature.

l he'dried residueffrom the ethylene --'di :hlori 'ie solution isreflt'ixed in '='nitromethan'e -'-for 1 one hour and filtered hot'(about '60C-=) and the filter cake washed with -cold nitrorhethane. 'lhe leachingfprocedure is repeated "by suspending the solids in refluxingmethanol for abolit 30 minutes. "Following this, the solids arerecove'red by 'filt'ration 'hot --'about C) anddried in -a'-vacuumoven-to Jprovide'sterols,which are about 'percent pure, i.e., free fro'moxidation "by products, high =molectilar weight acidsya'nd highmolecular al- 'c'ohols. l hestero'ls-so obtained comprise a mixture of 4about "92 ;percent fi sitos'terol and '8 percent camv Ipeste'rdl.

l'n step (A )'6f' the above p'rocess the high boiling z ptroleum' ethe'risweplacedbyanequivalent amount of low boilin'g ipetroleum ethe'r,kerosene, "light mineral" oil, iperitan'e, f'heptane, tridecane,ape'ntadecane, eicosai1 e,-'a'nd rnix t ures t'he'r'eof and equivalentresults are obtained th'a'ti'good separation oflthe fatty acids "fromthe ste'r'o'l source is achieved upon addition of =fro'r'n 0I 5ipereentto tfiipercentwaterfibasedon alcohol.

l'n step *(A) of the {above i'p'rocess thejmethanol is replaced with an*equivalent amount of ethanol,

h'exanol and isohe'xa'nol, respectively, and equivalent resu'ltsare"obtained in that good'separation of the 'fatty ac'ids froin theisterol "source *is achieved upon addition -of0Z5 percerit to Operceritwa'ten based'on alcohol.

ln step (-A) of the above process the high boiling p'etroleur'n'ether-metha'nol'solvent is replaced by a 5: 1

(-Wt.) h exane-me'tha'ndl 'sdlvent, a 1: 1 -'(wt.)hexanemethanolsolventja 1:5 '(wt.)hexane-m'ethanol solvent, a "551-('-Wt.") kerosene-methanolsolvent, a l :5 kerosenemethandl solvent, -"a'5 1 (wTt.-) {petroleum ether-ethanol solve'nt,-a 1-55 ipetroieumether-methanol solvent, a l l "hexane-hexano'l "solvent, a 5: 1'benzehe-propanol so'l- '-ve'nt,a l 55(wt.) hexane-ethanol solvent, a-'l l petrole- -um ether-methanol solvent, a '5:l petroleumethermth'andl "solvent and a 1:1 hexane-ethanol solvent,respectively,-and-good separation of the fatty acids is achieved uponaddition of from "0.5 to 10 percent 'watenfb'a'sedonalcohol.

In "step B o'ft'he above process the sodium hydroxide is replaced byaboirtaOJ-fold to 1 10-fold molar ex- 'cess df lithiilrn hydroxide,-potassium hydroxide. rubidiu'm hydroitidegand cesium hydroxide,respectively, and the 'saponification'ofthe steroles'ters 'is carriedout at temperatures d f"90F, "F and 500F, respectively, fo'r periodsof0.l,'0. 2, 2 and 5 hours, respectively. Equivaleiit results are=obtainedinthat-the sterol esters are-convertedtothe'free sterols which arehighlypure by'vittue-fdf the treatmentsip'rovided in'steps'(A), (C)

and-(D). Total s'terol-yields so-obtain'ed at temperatures fir90fQ and"120C are about '60 percent, based on original s te'roles'ters. Atthehigher saponification tem- 'pe'ra'tur es,essentially 80-90 percentyields of sterols "are obtained.

"In step ('8) of the above process the methanol 'saponi fica'tionsolvent is replaced by an equivalent amounto'iethanol,'propanoL-isopropanol, butanol, tbutanol, pentanol and hexanol',respectively, and equivalentf'r'esults are obtained in that the sterolesters are sa'ponifie'd.

. somewhat greater quantities than from the pure alcoholicsaponification solvent.

In step (D) of the above process the ethylene dichloride used todissolve the sterols and remove the insolubles is replaced by acetone,ethyl acetate, dimethylforrnamide, trichloroethylene, and methyl I ethylketone, respectively, with equivalent results.

In step (D) of the above process the leaching is done at 70F, -lF, 140F,300F and 500F (using pressure vessels), respectively, and the sterol ispurified.

In step (D) the nitromethane is replaced 'with methanol and the leachingis carried out at 70F, 100F, 140F and 300F, respectively, and the highmolecular weight alcohol contaminants are removed from the sterols.

What is claimed is: l. A process for preparing sterols from plantsources comprising the steps of: (A) dissolving a plant-derived sterolsource in a solvent mixture comprising an alcohol containing from aboutone to about six carbon atoms and a liquid hydrocarbon, and adding waterin an amount from about 0.5 to about percent by weight of alcohol andallowing the phases to separate; (B) saponifying. the sterol estersobtained from the hydrocarbon phase of step (A) with an alkali metalbase at a temperature from about 90F to about 500F in a lower alcoholsolvent; and (C) dissolving the sterols obtained from step (B) in apolar, aprotic organic solvent in which soaps are insoluble, discardingsaid soaps, recovering the sterols from the solvent and leaching thesterols with a solvent selected from the group consisting of methanoland nitro-methane at a temperature above about F.

2. A process according toclaim 1 wherein the plant source of the sterolis a member selected from the group consisting of tall oil pitch, crudetall oil, sugarcane oil, hot well skimmings, cottonseed pitch, soybeanpitch, corn oil pitch, wheat germ oil and rye germ oil.

3. A process according to claim 1' wherein the alcohol used in step (A)is selected from the group con-' sisting of methanol and ethanol and theliquid hydrocarbon used in step (A) is selected from the groupconsisting of hexane, kerosene, and petroleum ether.

4. A process according to claim 1 wherein about a 0.7-fold to about a1.0-fold molar excess of alkali metal base is used in the saponificationstep (B) and the saponification is carried out at a temperature fromabout 300F to about 500F.

5. A process according to claim 1 wherein the polar, aprotic organicsolvent used in step (D) to dissolve the sterols and separate the soapstherefrom is selected from the group consisting of methyl ethyl ketone,acetone and dichlorornethane.

6. A process according to claim 1 wherein the solvent used in theleaching operation of step (D) is methanol and the leaching is carriedout at temperatures from about 70F to about F.

2. A process according to claim 1 wherein the plant source of the sterolis a member selected from the group consisting of tall oil pitch, crudetall oil, sugar-cane oil, hot well skimmings, cottonseed pitch, soybeanpitch, corn oil pitch, wheat germ oil and rye germ oil.
 3. A processaccording to claim 1 wherein the alcohol used in step (A) is selectedfrom the group consisting of methanol and ethanol and the liquidhydrocarbon used in step (A) is selected from the group consisting ofhexane, kerosene, and petroleum ether.
 4. A process according to claim 1wherein about a 0.7-fold to about a 1.0-fold molar excess of alkalimetal base is used in the saponification step (B) and the saponificationis carried out at a temperature from about 300* F to about 500* F.
 5. Aprocess according to claim 1 wherein the polar, aprotic organic solventused in step (D) to dissolve the sterols and separate the soapstherefrom is selected from the group consisting of methyl ethyl ketone,acetone and dichloromethane.
 6. A process according to claim 1 whereinthe solvent used in the leaching operation of step (D) is methanol andthe leaching is carried out at temperatures from about 70* F to about140* F.